NAME

Catalyst::Upgrading - Instructions for upgrading to the latest Catalyst

Upgrading to Catalyst 5.90085

In this version of Catalyst we made a small change to Chained Dispatching so that when two or more actions all have the same path specification AND they all have Args(0), we break the tie by choosing the last action defined, and not the first one defined. This was done to normalize Chaining to following the 'longest Path wins, and when several actions match the same Path specification we choose the last defined.' rule. Previously Args(0) was hard coded to be a special case such that the first action defined would match (which is not the case when Args is not zero.)

Its possible that this could be a breaking change for you, if you had used action roles (custom or otherwise) to add additional matching rules to differentiate between several Args(0) actions that share the same root action chain. For example if you have code now like this:

The way that chaining will work previous is that when two or more equal actions can match, the 'top' one wins. So if the request is "GET .../check_default" BOTH actions 'default_get' AND 'chain_default' would match. To break the tie in the case when Args is 0, we'd previous take the 'top' (or first defined) action. Unfortunately this treatment of Args(0) is special case. In all other cases we choose the 'last defined' action to break a tie. So this version of Catalyst changed the dispatcher to make Args(0) no longer a special case for breaking ties. This means that the above code must now become:

If we want it to work as expected (for example we we GET to match 'default_get' and POST to match 'default_post' and any other http Method to match 'chain_default').

In other words Arg(0) and chained actions must now follow the normal rule where in a tie the last defined action wins and you should place all your less defined or 'catch all' actions first.

If this causes you trouble and you can't fix your code to conform, you may set the application configuration setting "use_chained_args_0_special_case" to true and that will revert you code to the previous behavior.

More backwards compatibility options with UTF-8 changes

In order to give better backwards compatiblity with the 5.90080+ UTF-8 changes we've added several configuration options around control of how we try to decode your URL keywords / query parameters.

do_not_decode_query

If true, then do not try to character decode any wide characters in your request URL query or keywords. Most readings of the relevent specifications suggest these should be UTF-* encoded, which is the default that Catalyst will use, hwoever if you are creating a lot of URLs manually or have external evil clients, this might cause you trouble. If you find the changes introduced in Catalyst version 5.90080+ break some of your query code, you may disable the UTF-8 decoding globally using this configuration.

This setting takes precedence over default_query_encoding and decode_query_using_global_encoding

default_query_encoding

By default we decode query and keywords in your request URL using UTF-8, which is our reading of the relevent specifications. This setting allows one to specify a fixed value for how to decode your query. You might need this if you are doing a lot of custom encoding of your URLs and not using UTF-8.

This setting take precedence over decode_query_using_global_encoding.

decode_query_using_global_encoding

Setting this to true will default your query decoding to whatever your general global encoding is (the default is UTF-8).

Upgrading to Catalyst 5.90080

UTF8 encoding is now default. For temporary backwards compatibility, if this change is causing you trouble, you can disable it by setting the application configuration option to undef:

MyApp->config(encoding => undef);

But please consider this a temporary measure since it is the intention that UTF8 is enabled going forwards and the expectation is that other ecosystem projects will assume this as well. At some point you application will not correctly function without this setting.

As of 5.90084 we've added two additional configuration flags for more selective control over some encoding changes: 'skip_body_param_unicode_decoding' and 'skip_complex_post_part_handling'. You may use these to more selectively disable new features while you are seeking a long term fix. Please review CONFIGURATION in Catalyst.

You will need to update to modern versions in most cases, although quite a few of these only needed minor test case and documentation changes so you will need to review the changelog of each one that is relevant to you to determine your true upgrade needs.

Upgrading to Catalyst 5.90060

Starting in the v5.90059_001 development release, the regexp dispatch type is no longer automatically included as a dependency. If you are still using this dispatch type, you need to add Catalyst::DispatchType::Regex into your build system.

The standalone distribution of Regexp will be supported for the time being, but should we find that supporting it prevents us from moving Catalyst forward in necessary ways, we reserve the right to drop that support. It is highly recommended that you use this last stage of deprecation to change your code.

Upgrading to Catalyst 5.90040

Catalyst::Plugin::Unicode::Encoding is now core

The previously stand alone Unicode support module Catalyst::Plugin::Unicode::Encoding has been brought into core as a default plugin. Going forward, all you need is to add a configuration setting for the encoding type. For example:

Please note that this is different from the old stand alone plugin which applied UTF-8 encoding by default (that is, if you did not set an explicit encoding configuration value, it assumed you wanted UTF-8). In order to preserve backwards compatibility you will need to explicitly turn it on via the configuration setting. THIS MIGHT CHANGE IN THE FUTURE, so please consider starting to test your application with proper UTF-8 support and remove all those crappy hacks you munged into the code because you didn't know the Plugin existed :)

For people that are using the Plugin, you will note a startup warning suggesting that you can remove it from the plugin list. When you do so, please remember to add the configuration setting, since you can no longer rely on the default being UTF-8. We'll add it for you if you continue to use the stand alone plugin and we detect this, but this backwards compatibility shim will likely be removed in a few releases (trying to clean up the codebase after all).

If you have trouble with any of this, please bring it to the attention of the Catalyst maintainer group.

basic async and event loop support

This version of Catalyst offers some support for using AnyEvent and IO::Async event loops in your application. These changes should work fine for most applications however if you are already trying to perform some streaming, minor changes in this area of the code might affect your functionality. Please see Catalyst::Response\write_fh for more and for a basic example.

We consider this feature experimental. We will try not to break it, but we reserve the right to make necessary changes to fix major issues that people run into when the use this functionality in the wild.

Regex dispatch type is deprecated.

If you cannot do so, please add a dependency to Catalyst::DispatchType::Regex to your application's Makefile.PL

Upgrading to Catalyst 5.9

The major change is that Plack, a toolkit for using the PSGI specification, now replaces most of the subclasses of Catalyst::Engine. If you are using one of the standard subclasses of Catalyst::Engine this should be a straightforward upgrade for you. It was a design goal for this release to preserve as much backwards compatibility as possible. However, since Plack is different from Catalyst::Engine, it is possible that differences exist for edge cases. Therefore, we recommend that care be taken with this upgrade and that testing should be greater than would be the case with a minor point update. Please inform the Catalyst developers of any problems so that we can fix them and incorporate tests.

It is highly recommended that you become familiar with the Plack ecosystem and documentation. Being able to take advantage of Plack development and middleware is a major bonus to this upgrade. Documentation about how to take advantage of Plack::Middleware by writing your own .psgi file is contained in Catalyst::PSGI.

Catalyst::Engine::Apache2::MP19, however, is no longer supported, as Plack does not support mod_perl version 1.99. This is unlikely to be a problem for anyone, as 1.99 was a brief beta-test release for mod_perl 2, and all users of mod_perl 1.99 are encouraged to upgrade to a supported release of Apache 2 and mod_perl 2.

Upgrading the HTTP Engine

The default development server that comes with the Catalyst distribution should continue to work as expected with no changes as long as your myapp_server script is upgraded to use Catalyst::Script::HTTP.

Applications that were using Catalyst::Engine::PSGI previously should entirely continue to work in this release with no changes.

However, if you have an app.psgi script, then you no longer need to specify the PSGI engine. Instead, the Catalyst application class now has a new method psgi_app which returns a PSGI compatible coderef which you can wrap in the middleware of your choice.

Catalyst will use the .psgi for your application if it is located in the home directory of the application.

For example, if you were using Catalyst::Engine::PSGI in the past, you will have written (or generated) a script/myapp.psgi file similar to this one:

my $app = sub { MyCatalystApp->psgi_app(@_) };
# If you make ^^ this mistake, your app won't work, and will confuse the hell out of you!

You can now move script/myapp.psgi to myapp.psgi, and the built-in Catalyst scripts and your test suite will start using your .psgi file.

NOTE: If you rename your .psgi file without these modifications, then any tests run via Catalyst::Test will not be compatible with the new release, and will result in the development server starting, rather than the expected test running.

NOTE: If you are directly accessing $c->req->env to get the PSGI environment then this accessor is moved to $c->engine->env, you will need to update your code.

Engines which are known to be broken

The following engines DO NOT work as of Catalyst version 5.9. The core team will be happy to work with the developers and/or users of these engines to help them port to the new Plack/Engine system, but for now, applications which are currently using these engines WILL NOT run without modification to the engine code.

Catalyst::Engine::Wx

Catalyst::Engine::Zeus

Catalyst::Engine::JobQueue::POE

Catalyst::Engine::XMPP2

Catalyst::Engine::SCGI

Engines with unknown status

The following engines are untested or have unknown compatibility. Reports are highly encouraged:

Plack functionality

Tests in 5.9

Tests should generally work the same in Catalyst 5.9, but there are some differences.

Previously, if using Catalyst::Test and doing local requests (against a local server), if the application threw an exception then this exception propagated into the test.

This behavior has been removed, and now a 500 response will be returned to the test. This change standardizes behavior, so that local test requests behave similarly to remote requests.

Upgrading to Catalyst 5.80

Most applications and plugins should run unaltered on Catalyst 5.80.

However, a lot of refactoring work has taken place, and several changes have been made which could cause incompatibilities. If your application or plugin is using deprecated code, or relying on side effects, then you could have issues upgrading to this release.

Most issues found with existing components have been easy to solve. This document provides a complete description of behavior changes which may cause compatibility issues, and of new Catalyst warnings which might be unclear.

If you think you have found an upgrade-related issue which is not covered in this document, please email the Catalyst list to discuss the problem.

Moose features

Application class roles

You can only apply method modifiers after the application's ->setup method has been called. This means that modifiers will not work with methods run during the call to ->setup.

Known backwards compatibility breakages

Applications in a single file

Applications must be in their own file, and loaded at compile time. This issue generally only affects the tests of CPAN distributions. Your application will fail if you try to define an application inline in a block, and use plugins which supply a new method, then use that application latter in tests within the same file.

This is due to the fact that Catalyst is inlining a new method on your application class allowing it to be compatible with Moose. The method used to do this changed in 5.80004 to avoid the possibility of reporting an 'Unknown Error' if your application failed to compile.

Issues with Class::C3

Catalyst 5.80 uses the Algorithm::C3 method dispatch order. This is built into Perl 5.10, and comes via Class::C3 for Perl 5.8. This replaces NEXT with Class::C3::Adopt::NEXT, forcing all components to resolve methods using C3, rather than the unpredictable dispatch order of NEXT.

This issue manifests itself by your application failing to start due to an error message about having a non-linear @ISA.

The Catalyst plugin most often causing this is Catalyst::Plugin::Session::Store::FastMmap - if you are using this plugin and see issues, then please upgrade your plugins, as it has been fixed. Note that Makefile.PL in the distribution will warn about known incompatible components.

This issue can, however, be found in your own application - the only solution is to go through each base class of the class the error was reported against, until you identify the ones in conflict, and resolve them.

To be able to generate a linear @ISA, the list of superclasses for each class must be resolvable using the C3 algorithm. Unfortunately, when superclasses are being used as mixins (to add functionality used in your class), and with multiple inheritance, it is easy to get this wrong.

Most common is the case of:

package Component1; # Note, this is the common case
use base qw/Class::Accessor::Fast Class::Data::Inheritable/;
package Component2; # Accidentally saying it this way causes a failure
use base qw/Class::Data::Inheritable Class::Accessor::Fast/;
package GoesBang;
use base qw/Component1 Component2/;

Components which inherit from Moose::Object before Catalyst::Component

to use the constructor provided by Moose, while working (if you do some hacks with the BUILDARGS method), will not work with Catalyst 5.80 as Catalyst::Component inherits from Moose::Object, and so @ISA fails to linearize.

The correct way to use Moose in a component in a both forward and backwards compatible way is:

Note that the extends declaration needs to occur in a begin block for attributes to operate correctly.

This way you do not inherit directly from Moose::Object yourself. Having components which do not inherit their constructor from Catalyst::Component is unsupported, and has never been recommended, therefore you're on your own if you're using this technique. You'll need to detect the version of Catalyst your application is running, and deal with it appropriately.

You also don't get the Moose::Object constructor, and therefore attribute initialization will not work as normally expected. If you want to use Moose attributes, then they need to be made lazy to correctly initialize.

Note that this only applies if your component needs to maintain component backwards compatibility for Catalyst versions before 5.71001 - in 5.71001 attributes work as expected, and the BUILD method is called normally (although BUILDARGS is not).

If you depend on Catalyst 5.8, then all Moose features work as expected.

Anonymous closures installed directly into the symbol table

If you have any code which installs anonymous subroutine references directly into the symbol table, you may encounter breakages. The simplest solution is to use Sub::Name to name the subroutine. Example:

Hooking into application setup

With Catalyst 5.80 this won't work anymore, because Catalyst no longer uses NEXT.pm for method resolution. The functionality was only ever originally operational as NEXT remembers what methods have already been called, and will not call them again.

Using this now causes infinite recursion between MyApp::setup and Catalyst::setup, due to other backwards compatibility issues related to how plugin setup works. Moose method modifiers like before|after|around setup => sub { ... }; also will not operate correctly on the setup method.

The right way to do it is this:

after setup_finalize => sub {
... # things to do after the actual setup
};

The setup_finalize hook was introduced as a way to avoid this issue.

Components with a new method which returns false

Previously, if you had a component which inherited from Catalyst::COMPONENT, but overrode the new method to return false, then your class's configuration would be blessed into a hash on your behalf, and this would be returned from the COMPONENT method.

This behavior makes no sense, and so has been removed. Implementing your own new method in components is highly discouraged. Instead, you should inherit the new method from Catalyst::Component, and use Moose's BUILD functionality and/or Moose attributes to perform any construction work necessary for your class.

__PACKAGE__->mk_accessor('meta');

Won't work due to a limitation of Moose. This is currently being fixed inside Moose.

Class::Data::Inheritable side effects

Previously, writing to a class data accessor would copy the accessor method down into your package.

This behavior has been removed. While the class data is still stored per-class, it is stored on the metaclass of the class defining the accessor.

Therefore anything relying on the side effect of the accessor being copied down will be broken.

Extending Catalyst::Request or other classes in an ad hoc manner using mk_accessors

Previously, it was possible to add additional accessors to Catalyst::Request (or other classes) by calling the mk_accessors class method.

This is no longer supported - users should make a subclass of the class whose behavior they would like to change, rather than globally polluting the Catalyst objects.

Confused multiple inheritance with Catalyst::Component::COMPONENT

Previously, Catalyst's COMPONENT method would delegate to the method on the right hand side, which could then delegate back again with NEXT. This is poor practice, and in addition, makes no sense with C3 method dispatch order, and is therefore no longer supported.

If a COMPONENT method is detected in the inheritance hierarchy to the right hand side of Catalyst::Component::COMPONENT, then the following warning message will be emitted:

There is a COMPONENT method resolving after Catalyst::Component
in ${next_package}.

The correct fix is to re-arrange your class's inheritance hierarchy so that the COMPONENT method you would like to inherit is the first (left-hand most) COMPONENT method in your @ISA.

Development server relying on environment variables

Previously, the development server would allow propagation of system environment variables into the request environment, this has changed with the adoption of Plack. You can use Plack::Middleware::ForceEnv to achieve the same effect.

WARNINGS

Actions in your application class

Having actions in your application class will now emit a warning at application startup as this is deprecated. It is highly recommended that these actions are moved into a MyApp::Controller::Root (as demonstrated by the scaffold application generated by catalyst.pl).

This warning, also affects tests. You should move actions in your test, creating a myTest::Controller::Root, like the following example:

::[MVC]:: naming scheme

Having packages called MyApp::[MVC]::XX is deprecated and can no longer be generated by catalyst.pl

This is still supported, but it is recommended that you rename your application components to Model/View/Controller.

A warning will be issued at application startup if the ::[MVC]:: naming scheme is in use.

Catalyst::Base

Any code using Catalyst::Base will now emit a warning; this module will be removed in a future release.

Methods in Catalyst::Dispatcher

The following methods in Catalyst::Dispatcher are implementation details, which may change in the 5.8X release series, and therefore their use is highly deprecated.

tree

dispatch_types

registered_dispatch_types

method_action_class

action_hash

container_hash

The first time one of these methods is called, a warning will be emitted:

Class $class is calling the deprecated method Catalyst::Dispatcher::$public_method_name,
this will be removed in Catalyst 5.9

You should NEVER be calling any of these methods from application code.

Plugin authors and maintainers whose plugins currently call these methods should change to using the public API, or, if you do not feel the public API adequately supports your use case, please email the development list to discuss what API features you need so that you can be appropriately supported.

Class files with names that don't correspond to the packages they define

In this version of Catalyst, if a component is loaded from disk, but no symbols are defined in that component's name space after it is loaded, this warning will be issued:

require $class was successful but the package is not defined.

This is to protect against confusing bugs caused by mistyping package names, and will become a fatal error in a future version.

Please note that 'inner packages' (via Devel::InnerPackage) are still fully supported; this warning is only issued when component file naming does not map to any of the packages defined within that component.

$c->plugin method

Calling the plugin method is deprecated, and calling it at run time is highly deprecated.

Instead you are recommended to use Catalyst::Model::Adaptor or similar to compose the functionality you need outside of the main application name space.